Glossary of Wine Making Terminology

If you’re new to home wine making, the sheer volume of new terms alone can be daunting. It’s kind of like learning a new language, though – even after you’ve made a few batches, you’ll discover new terms that you haven’t heard before.

This alphabetical glossary of wine making terms was assembled with that long learning curve in mind!

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acidity – what gives wine (along with most other drinks) its tang. Lemons have lots of it; potatoes have very little. A wine's acidity comes from the acids (mainly malic and tartaric) in grape juice, which diminish as grapes ripen. A hot summer may reduce acids to such an extent that some have to be added, a process known as acidification.

acids – group of chemical compounds that give grape juice and wine their tang and ability to refresh. Most common acids in grape juice are tartaric and malic.

American hybrid – variety bred from American and European vines

ampelography – science of identifying grape varieties by detailed description of the appearance of the vine, especially its leaves

alcohol – the potent mood-changer that differentiates wine from grape juice. A wine's alcoholic strength is its concentration of alcohol.

analysis – operation to which almost all modern wine is subjected. Analysis measures a wine’s vital statistics – alcoholic strength, total acidity, and residual sugar – as well as other factors.

anthocyans – phenolics that most strongly influence a red wine's color, which is directly affected by its pH

ascorbic acid or vitamin C – chemical often added to must during wine making since it prevents oxidation. It is often used together with sulfur dioxide to keep white wines fresh.

barrel – the wine maker's most fashionable tool

barrel aging – keeping wine in a cask between fermentation and bottling so that it stabilizes naturally in the presence of small amounts of air. During barrel aging a wine absorbs some flavor and possibly tannins from the wood, depending on the wood’s age, the size of the barrel, and the duration of barrel aging.

barrel fermentation – fermentation in small barrels rather than a large tank. This is common for top quality white wine.

chaptalization – common cool climate wine making procedure that compensates for under-ripe grapes by adding sugar to the fermentation vat in order to produce a more alcoholic wine. This technique was named after French statesman Jean Antoine Chaptal and is usually strictly controlled.

classed growth or classified growth – English version of the French term cru classés. This term is used in Bordeaux for the 60 or so wine estates, or crus, that were included in the 1855 classification of the top Médoc and Graves region estates. They were ranked, as in football divisions, into first (premier), second (deuxième), third (troisième), fourth (quatrième) and fifth (cinquième) growths. There are only five first growths: Château Lafite-Rothschild, Château Latour, Château Margaux, Château Mouton Rothschild, and Château Haut-Brion.

clarification – umbrella term for a host of processes designed to ensure wine is crystal clear, including fining, filtration and refrigeration

clone – an example of a grape variety replicated from a particular mother vine specially selected for a specific attribute or set of attributes

concentration – new technique for concentrating flavor (and acid and tannin) in less ripe vintages

coulure – deficient fruit set which may substantially reduce the size of that year's crop. Just after flowering, an excessive proportion of the nascent berries fall off, often because of cold, wet weather. Some varieties are more prone than others.

élevage – French term for the wine-maturing processes involved between fermentation and bottling; the closest term in English is raising

enology – the science of wine making, usually practiced by a qualified enologist

ethyl alcohol or ethanol – the sort of alcohol found in alcoholic drinks such as wine

fanleaf – viral vine disease

fermentation – the process whereby sweet grape juice is transformed into alcoholic wine due to the action of yeast

field grafting – the increasingly common practice of grafting a new variety onto an established rootstock in the vineyard

filtration – controversial clarification process of pumping wine through different kinds of filters to remove suspended solids. The process may also strip out flavor if overdone.

fining – clarification technique involving adding a fining agent such as egg whites or bentonite. The fining agent attracts solids which then fall to the bottom of a container, making them easier to remove from the wine.

flavor compounds – complex, still under-explored maze of phenolics responsible for the flavors of different wines.

foxy – distinctive taste of the grapes and wine of some American vines, especially Vitis labrusca and some of its hybrids. Methyl anthranilate is often the offending compound.

free-run – the name given to juice or wine that flows without pressing

French hybrid – vine variety bred from American and European parents

fruit set – early summer phenomenon that immediately follows flowering. As soon as the vine flowers, a proportion of them are fertilized, or “set”, to become berries and eventually grapes. The higher the proportion, the bigger the crop is likely to be.

grafting –inserting a section of one plant into another so that they unite and grow as one plant. In a viticultural context, usually this refers to grafting a European fruiting vine onto a rootstock that is chosen for its resistance to phylloxera.

ha – abbreviation for hectare, or 2.47 acres

hl – abbreviation for hectoliter: 100 liters or 26.4 US gallons

hybrid – variety bred from members of different species

inert gas – a gas such as nitrogen that does not react with wine. Inert gases can be used to fill the head space of a container to prevent oxidation.

leafroll – viral vine disease

lees – the solids left at the bottom of a fermentation vat after fermentation. Relatively neutral-tasting white wines are often deliberately given prolonged lees contact and even lees stirring to generate more flavor and make them more stable.

malic acid – an acid with a sharp apple-like flavor that is most notable in grapes from cool years

malolactic fermentation, MLF or le malo – increasingly common second fermentation in which harsh malic acid is converted to softer, milky tasting lactic acid. Generally this process results in a more supple wine.

mercaptan – wine fault that was once more common in Australian wines. A skunky smell results from yeast reacting with sulfur in the lees. It can be avoided by assiduous racking.

millerandage – abnormal fruit set in which bunches contain berries of very different sizes because of poor fertilization, often because of unfavorable weather

must – useful word for the pulpy mass at any stage between grape juice and wine.

must weight – measure of grape ripeness, or sugar concentration, in grapes

noble rot – the benevolent form of botrytis

oak – the most common sort of wood used for wine barrels. Usually either soft, sweetish American oak or more savory French oak are used.

oxidation – potentially serious calamity that can strike grapes, grape juice and wine if they are ove-exposed to oxygen, making them go brown (like a cut apple) and taste flat. Many times this culprit is a less-than-airtight stopper.

oxygen – both good and bad fairy in the wine making process. A small amount of oxygen at the beginning of fermentation encourages the yeast. During barrel maturation oxygen deepens a wine’s color, smoothes its flavor and makes it more stable. But too much oxygen causes oxidation and may eventually turn the wine to vinegar.

pH – a measure of the concentration of acidity in a liquid. Higher pH numbers mean lower acid. Water, for example, has a pH of 7. Most wines have a pH between 3 and 4; very acidic wines have a pH of less than 3. pH and color are also closely related.

phenolics – varied group of compounds; in grapes they are found mainly in the skins, stems and seeds. They include anthocyans, tannins and many flavor compounds. Precipitated, they form an important part of wine's sediment and play a considerable role in wine aging. Red wines are much higher in phenolics than white.

phylloxera – fatal insect pest that chews vine roots. The only remedy is to replant on phylloxera-resistant rootstocks.

potential alcohol – the alcoholic strength a liquid would reach if all the sugar were fermented into alcohol

powdery mildew – fungal disease of the vine

pressing – important wine making operation involving literally pressing the juice out of the grapes or other fruit being used to make the wine. The quality of the resulting juice depends on how hard the grapes are pressed.

protective wine making – protecting the grapes, juice, must and wine from oxygen, typically by using sealed containers, low temperatures, sulfur dioxide or sometimes ascorbic acid

pruning – arguably the most important operation of the vineyard year in terms of wine quality. During winter the vine is cut back, leaving a specific number of buds responsible for producing the next year's crop. Although many other factors come into play, low-yielding vines in general tend to produce more concentrated wine.

pulp – the fleshy part of the grape containing most of the water, sugars and acids in grape juice. Apart from red fleshed Teinturiers, the flesh of all grapes is the same dull grey, no matter what the color of the grape's skin.

racking – the operation of transferring wine from one container (typically a barrel) to another, leaving behind the lees. It can usefully expose the wine to oxygen and avoid reduction.

residual sugar or RS – the amount of unfermented sugar left in a wine after fermentation is complete, usually measured in grams per liter (g/l) or percent. A residual sugar level of less than 2 g/l (0.02%) is imperceptible to most palates. Although acidity counterbalances residual sugar, most wines with 25 g/l (2.5%) residual sugar taste distinctly sweet.

reducing conditions – conditions that favor reduction, or loss of oxygen. This is the opposite of oxidation. When overdone, where a (usually red) wine is starved of oxygen, this can result in off-putting mercaptan or sulfide smells.

rootstock – plant specially selected to form the root system of a fruiting vine of another variety through grafting

seed – part of the grape containing tannins. Care is usually taken not to crush them.

skin – very important part of the grape that contains most flavor compounds, pigments, and tannins. All of these are highly desirable, not to say essential, for red wines – but they are more debatable ingredients in the white wine making process

skin contact – deliberate policy of trying to extract as many flavor compounds and/or anthocyans as possible from grape skins into juice (in the case of white wines) or wine (in the case of reds)

sorbic acid – additive widely used in the food and drink industries to stun yeasts and molds. Sometimes used for inexpensive sweet wines, it smells of crushed geranium leaves; a small proportion of people are extremely sensitive to it.

soutirage – French for racking

stabilization – umbrella term for all the wine making operations designed to keep wines from developing a fault in the bottle such as a haze, cloud or fizz, no matter what the storage conditions. It is practiced most brutally on everyday wines.

stem or stalk – woody attachment of the grape to the bunch, often high in harsh tannins. All or most are usually deliberately eliminated by a mechanical destemmer prior to fermentation.

sulfur dioxide – the most common and most useful wine making additive since Roman times, used mainly as a preservative, disinfectant and to ward off oxidation. Its use has been declining as consumers have become less tolerant of the freshly-struck match smell associated with sulfur. Some asthmatics also react badly to high doses of sulfur, which has lead to some countries' requiring the legend “contains sulfites/sulphites” on wine labels. A tiny but increasing proportion of wines are made using no sulfur at all but they tend to be more fragile than most. Sulfur reacts readily with many other wine ingredients to form bound sulfur; it is only free sulfur which can be detected, although sensitivities vary considerably between individuals.

sugar – carbohydrates accumulated in the grape pulp during the ripening process. Sugars are transformed into alcohol by fermentation. See also chaptalization.

tannins – cheek-drying, astringent phenolic compounds similar to stewed tea in effect on the palate. Tannins are found mainly in red wine and are derived from grape seeds, skins, and stems. They can help preserve red wines while they mature in bottle. Tannin management is one of the red wine maker's most important jobs.

tartaric acid – the most common and distinctive wine acid that serves as a particularly good preservative. A lot of the acid is precipitated as crusty deposits called tartrates, usually seen as harmless white crystals in white wine and dyed deep red in red wines.

training – shaping a vine into a specific shape, usually to effect some form of canopy management

triage – French word for sorting. In viticulture triage usually refers to sorting grapes for health and quality in the vineyard or as they are brought in to the winery.

ullage – the head space between the wine and the top of a container such as a barrel or bottle. If it is excessive it can cause oxidation.

vieilles vignes – French for “old vines”, which generally produce more concentrated wine than young ones

vigor – a vine's natural tendency to sprout leaves

vine density – important vineyard parameter that corresponds to the number of vines planted per unit of area

vinifera – vine species of European origin, as almost all the well-known wine producing varieties are

vintage – can mean either the particular year in which the crop was harvested or the process of harvesting itself

Vitis – the vine genus

whole bunchpressing and fermentation – this is an alternative to destemming before pressing or fermenting. These two techniques, common in Champagne and Burgundy respectively, physically help drainage, the stems acting as conduits.

yeast – micro-organism of many types that can encourage all sorts of chemical changes, including fermentation. Traditional wine producers tend to rely on ambient, invisible yeasts whereas modernists prefer specially cultured yeasts chosen for their suitability for a particular fermentation.

yield – the amount of wine or grapes produced per unit area, usually measured either as ton/acre, or, in much of Europe, hl/ha. Many factors such as pressing regime, grape variety, and style of wine affect the conversion of weight of grapes into volume of wine, but 1 ton/acre is very approximately equivalent to 17.5 hl/ha.

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